Systems and methods for object detection by radio frequency systems

ABSTRACT

Systems, methods, and devices are provided for detecting the presence of an object near an electronic device. A radio frequency (RF) system of an electronic device may include a first circuit that includes one or more transmission paths for transmitting a reference signal external to the electronic device. The RF system may include a second circuit that includes one or more receiving paths for receiving a reflection signal based on the reference signal. The RF system may also include a processor that may instruct the RF system to perform a comparison between the reference signal and the reflection signal, determine whether the object is in proximity based at least in part on whether comparison results exceed a comparison threshold, and decrease power output by the RF system below the comparison threshold.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/362,124, filed Mar. 22, 2019, entitled “SYSTEMS AND METHODS FOROBJECT DETECTION BY RADIO FREQUENCY SYSTEMS,” the disclosure of which isincorporated herein by reference in its entirety for all purposes.

BACKGROUND

The present disclosure relates generally to radio frequency systems and,more particularly, to using the radio frequency system to detect nearbyobjects and adjusting system operations to comply with energy absorption(e.g., specific absorption rate (SAR), maximum permissible exposure(MPE)) specifications when the object is detected by the radio frequencysystem.

This section is intended to introduce the reader to various aspects ofart that may be related to various aspects of the present disclosure,which are described and/or claimed below. This discussion is believed tobe helpful in providing the reader with background information tofacilitate a better understanding of the various aspects of the presentdisclosure. Accordingly, it should be understood that these statementsare to be read in this light, and not as admissions of prior art.

Electronic devices, such as smartphones and laptops, often include aradio frequency system to facilitate wireless communication of data withother electronic devices and/or networks. To facilitate the wirelesscommunication, the radio frequency system may emit energy in the form ofradio waves. In some cases, the emitted energy may be absorbed by anobject (e.g., a human body) that is within proximity to the radiofrequency system. The allowable amount of energy that may be absorbed bysuch an object may be regulated, and to ensure that these absorptionspecifications are met, the radio frequency system may lower energy(e.g., power) output when the object is nearby. However, traditionalradio frequency systems may be incapable of detecting the presence of anobject and thus, must output lower than maximum energy during all timesof operation. Operating at a lower than maximum energy output may resultin performance inefficiency of the radio frequency system.

SUMMARY

A summary of certain embodiments disclosed herein is set forth below. Itshould be understood that these aspects are presented merely to providethe reader with a brief summary of these certain embodiments and thatthese aspects are not intended to limit the scope of this disclosure.Indeed, this disclosure may encompass a variety of aspects that may notbe set forth below.

The present disclosure generally relates to adjusting radio frequencysystem operations when an object (e.g., a human body) is withinproximity by using existing radio frequency system hardware as a radarto detect the presence of an object and modifying energy (e.g., power)output by the radio frequency system accordingly. Radio frequencysystems of electronic devices may employ 5G New Radio (NR)millimeter-wave (mmWave) technology and/or one of sub-6 GHz technologies(e.g., 4G LTE, 5G NR sub-6 GHz, non-mmWave technologies, and the like).Such radio frequency systems must comply with regulations (e.g., maximumpermissible exposure (MPE) or specific absorption rate (SAR),respectively) on the rate at which energy carried by wireless signalsare absorbed by the human body. To comply with the MPE or the SARdepending on the radio frequency technology implemented, the radiofrequency system may output lower than maximum output power when thehuman body is near the radio frequency system. However, in many cases,the radio frequency system may be incapable of detecting the presence ofthe nearby human body and thus, must output lower than maximum outputpower at nearly all operation times. In such instances, the performanceand operational efficiency of the radio frequency system may be reduced.

To ensure compliance with the MPE or SAR while avoiding compromises onthe radio frequency system performance, in some embodiments, existingradio frequency hardware may be implemented to detect the presence ofthe nearby human body, and the output of the radio frequency system maybe adjusted accordingly. In some embodiments, the hardware may beimplemented as a bi-static radar with multiple transmitting/receivingcircuits (e.g., quads). A first quad of the bi-static radar may transmita 5G NR signal of a first polarization to an external environment. Asecond quad of the bi-static radar may receive a reflection of thetransmitted 5G NR signal using a second polarization. The reflected 5GNR signal, for example, may be generated when the transmitted 5G NRsignal is reflected off the human body. The radio frequency system mayperform a comparison between the transmitted 5G NR signal and thereflected 5G NR signal to determine whether the human body is withinproximity to the device. In this example, based on the comparison, theradio frequency system may adjust its output power to meet the MPE. Insome embodiments, when the sub-6 GHz technology is used, the radiofrequency system may adjust its output power to meet the SAR.

In some embodiments, the hardware may be implemented as a mono-staticradar. For example, the mono-static radar may transmit the 5G NR signaland receive the reflected 5G NR signal using a singletransmitting/receiving quad and polarization. The mono-static radar mayuse circuit components, such as bi-directional couplers and envelopedetectors, to facilitate transmitting and receiving the 5G NR signalusing the single quad. Further, the radio frequency system may perform acomparison between the transmitted 5G NR signal and the reflected 5G NRsignal to determine whether the human body is within proximity to thedevice. Based on the comparison, the radio frequency system may adjustits output power to meet the MPE. In some embodiments, when the sub-6GHz technology is used, the radio frequency system may adjust its outputpower to meet the SAR.

Further, in some embodiments, the hardware may be implemented as a BodyDetection Sensor operating in the 24 giga-hertz (GHz) band. Inparticular, multiple transmitting/receiving quads or a singletransmitting/receiving quad may be used to detect the presence of thehuman body, in a manner similar to that of the bi-static and mono-staticradars, respectively. For example, the first quad may use the existing24 GHz band to transmit a chirp (e.g., non-5G NR impulse response)signal of a first polarization, and the second quad may receive thereflected chirp signal using a second polarization. As another example,a single quad may transmit the chirp signal and may receive a reflectionof the chirp signal using a single polarity. The radio frequency systemmay perform a comparison between the transmitted chirp signal and thereflected chirp signal to determine whether the human body is withinproximity to the device. Based on the comparison, the radio frequencysystem may adjust its output power to meet the MPE. In some embodiments,when the sub-6 GHz technology is used, the radio frequency system mayadjust its output power to meet the SAR.

BRIEF DESCRIPTION OF THE DRAWINGS

Various aspects of this disclosure may be better understood upon readingthe following detailed description and upon reference to the drawings inwhich:

FIG. 1 is a block diagram of an electronic device with a radio frequencysystem, in accordance with an embodiment;

FIG. 2 is a front view of a hand-held device representing an example ofthe electronic device of FIG. 1 , in accordance with an embodiment;

FIG. 3 is a front view of another hand-held device representing anotherexample of the electronic device of FIG. 1 , in accordance with anembodiment;

FIG. 4 is a perspective view of a notebook computer representing anotherexample of the electronic device of FIG. 1 , in accordance with anembodiment;

FIG. 5 is a front view of a wearable electronic device representinganother example of the electronic device of FIG. 1 , in accordance withan embodiment;

FIG. 6 is a schematic of hardware of the radio frequency system of FIG.1 implemented as a bi-static radar to detect the presence of a humanbody, in accordance with an embodiment;

FIG. 7 is a schematic of the hardware of the radio frequency system ofFIG. 1 implemented as a mono-static radar to detect presence of thehuman body, in accordance with an embodiment;

FIG. 8 is a schematic of the hardware of the radio frequency system ofFIG. 1 implemented as a Body Detection Sensor operating in the 24giga-hertz (GHz) band to detect the presence of the human body, inaccordance with an embodiment; and

FIG. 9 is a flow chart of a process for adjusting operations of theradio frequency system of FIG. 1 based at least in part on the detectionof the human body by the radio frequency system of FIG. 1 , inaccordance with an embodiment.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

One or more specific embodiments will be described below. In an effortto provide a concise description of these embodiments, not all featuresof an actual implementation are described in the specification. Itshould be appreciated that in the development of any such actualimplementation, as in any engineering or design project, numerousimplementation-specific decisions must be made to achieve thedevelopers' specific goals, such as compliance with system-related andbusiness-related constraints, which may vary from one implementation toanother. Moreover, it should be appreciated that such a developmenteffort might be complex and time consuming, but would nevertheless be aroutine undertaking of design, fabrication, and manufacture for those ofordinary skill having the benefit of this disclosure.

When introducing elements of various embodiments of the presentdisclosure, the articles “a,” “an,” and “the” are intended to mean thatthere are one or more of the elements. The terms “comprising,”“including,” and “having” are intended to be inclusive and mean thatthere may be additional elements other than the listed elements.Additionally, it should be understood that references to “oneembodiment” or “an embodiment” of the present disclosure are notintended to be interpreted as excluding the existence of additionalembodiments that also incorporate the recited features.

The present disclosure generally relates to radio frequency systems usedto facilitate wireless communication of data between electronic devicesand/or with a network. For example, the radio frequency system maywirelessly communicate data by transmitting wireless signals (e.g.,radio waves) modulated in a manner representative of the data, forexample, via a personal area network (e.g., Bluetooth network), a localarea network (e.g., an 802.11x Wi-Fi network), and/or a wide areanetwork (e.g., a 4G, 5G, or LTE cellular network).

In particular, the radio frequency system may implement millimeter-wave(mmWave) wireless communication technologies due to large amounts ofavailable bandwidth in millimeter frequency bands that are capable ofsupporting high rates of information transfer. As an example, the radiofrequency system may use Fifth-Generation New Radio millimeter-wave(e.g., 5G NR mmWave) wireless technology or 5G NR Sub-6 GHz (e.g.,hereinafter “sub-6 GHz”) technology to facilitate better connection andmore efficient data transfer between electronic devices.

Such radio frequency systems may emit energy in the form of radio waves(e.g., wireless signals) to facilitate data transfer. In some instances,the emitted energy may be absorbed by an object (e.g., a human body)that is within proximity to the radio frequency system. The rate atwhich the emitted energy may be absorbed is regulated by a MaximumPermissible Exposure (MPE) limit for 5G NR mmWave systems and by aSpecific Absorption Rate (SAR) set for sub-6 GHz systems. In particular,for mmWave technologies, the wavelength of the radio frequency waves issmall enough for the human body to be considered as part of a far-fieldof the electronic device and thus, MPE (e.g., electromagnetic fieldincident on an object's surface, such as human skin, in Watts/meter²)may be used as an appropriate limit for emitted energy absorbed by anobject. On the other hand, for sub-6 GHz technology, the wavelength ofthe radio frequency waves used is larger compared to that of the mmWaveradio frequency waves and thus, the human body may be considered as partof a near-field of the electronic device. In such embodiments, the SAR(e.g., electromagnetic field through a volume, such as human tissue, orpower absorbed per mass of volume in Watts/kilogram) may provide abetter comparison limit for emitted energy absorbed by an object.

To comply with the MPE or SAR, the radio frequency system may outputlower than maximum output energy (e.g., output power) when the humanbody is near the electronic device, such as a hand-held device. Itshould be noted that while this disclosure contemplates compliance withthe MPE or SAR for nearby human bodies, any object or number of objectsthat may absorb emitted radio wave energy may be considered. Further, itshould be appreciated that the following techniques may be applicable toany mmWave system architecture.

In some cases, specialized circuitry (e.g., 60 GHz Body ProximitySensor) may be implemented in the radio frequency system to detect thepresence of the nearby human body. However, implementation of suchspecialized circuitry may be technically challenging and costly. Forexample, the specialized circuitry may not be compatible with the mmWavecircuitry and the specialized circuitry may increase silicon areaconsumed per radio frequency system chip.

Thus, in many instances, the radio frequency system may not have thecapability for detecting the presence of the nearby human body. This mayresult in the radio frequency system outputting lower than maximumoutput power during all operating (e.g., online) times to ensurecompliance with the MPE or SAR at all times. However, outputtingwireless signals with lower than maximum output power during onlineoperation may reduce the performance of the radio frequency system.Accordingly, the present disclosure provides systems and techniques fordetecting the presence of the nearby human body and modifying systemoperations to comply with the MPE for mmWave and the SAR for sub-6 GHzsystems without compromising system performance.

In particular, the hardware of the radio frequency system may beimplemented to detect the presence of the nearby human body. In someembodiments, the radio frequency system may employ hardware tailored tobetter suit wireless transmission via mmWave communication technology,such as the 5G NR mmWave technology. As an example, an electronic deviceusing 5G wireless technology may employ multiple transmission (TX) paths(e.g., chains), multiple reception (RX) paths, and multiple antennaelements. The TX paths, RX paths, and antenna elements may be dividedinto groups (e.g., quads) that together form a phased array antenna totransmit and/or receive wireless signals via particular signalpolarizations and via beams. The beams may communicate information in aparticular direction while reducing data loss that may occur over theair at 5G frequencies.

With the foregoing in mind, in some embodiments, the hardware of theradio frequency system may be implemented as a bi-static radar. One ormore TX paths within a first quad may transmit a 5G NR signal of a firstpolarization to an environment external to the electronic device. One ormore RX paths within a second quad may detect a reflection of thetransmitted 5G NR signal using a second polarization. The reflected 5GNR signal may be generated when the transmitted 5G NR signal isreflected off of the nearby human body. The radio frequency system mayperform a cross-correlation measurement of the transmitted 5G NR signaland the reflected NR signal to determine whether the human body iswithin proximity to the electronic device. Based on thecross-correlation measurement, the radio frequency system may reduceemitted output power to comply with the MPE or the SAR when the humanbody is detected nearby.

Further, in some embodiments, the hardware of the radio frequency systemmay be implemented as a mono-static radar. For example, the mono-staticradar may transmit the 5G NR signal and receive the reflected 5G NRsignal using a single transmitting/receiving quad and polarization. Themono-static radar may include a bi-directional coupler in the TX path ofthe single quad as well as envelope detectors associated with each ofthe TX paths of the single quad. The bi-directional coupler and envelopedetectors may facilitate detection of the reflected 5G NR signal. Theradio frequency system may analyze the phase delay difference betweenthe transmitted 5G NR signal and the reflected 5G NR signal. The radiofrequency system may subsequently perform a cross-correlation on thetransmitted 5G NR signal and the reflected 5G NR signal to determine thepresence of the nearby human body. Based on the cross-correlationmeasurement, the radio frequency system may reduce emitted output powerto comply with the MPE or the SAR when the human body is detectednearby.

Additionally or alternatively, in some embodiments, the hardware of theradio frequency system may be implemented as a Body Detection Sensoroperating in the 24 giga-hertz (GHz) industrial, scientific, medical(ISM) band (e.g., 24-24.25 GHz). Using either multiple quads andpolarizations or a single quad and polarization, the 24 GHz sensor maytransmit a chirp (e.g., non-5G NR impulse response) signal via the 24GHz ISM band and may detect a reflection of the transmitted chirpsignal. Further, the radio frequency system may perform across-correlation of the transmitted chirp signal and the reflectedchirp signal to determine the presence of the nearby human body. Basedon the cross-correlation result, the radio frequency system may reduceemitted output power to comply with the MPE or the SAR when the humanbody is detected nearby. Further, the radio frequency system may usingthe 24 GHz sensor technique during measurement gaps (e.g., periodsduring which the electronic device does not have up-link or down-linktransmissions scheduled) defined by 3^(rd) Generation PartnershipProject (3GPP) 5G NR standard. Additional details with regard to thedetection of the nearby human body using the embodiments describedherein are detailed below with reference to FIGS. 1-9 .

As such, an embodiment of an electronic device 10 that includes a radiofrequency system 12 is shown in FIG. 1 . As will be described in moredetail below, the electronic device 10 may be any suitable electronicdevice, such as a computer, a mobile phone, a portable media device, atablet, a television, a virtual-reality headset, a vehicle dashboard,and the like. Thus, it should be noted that FIG. 1 is merely one exampleof a particular implementation and is intended to illustrate the typesof components that may be present in an electronic device 10.

In the depicted embodiment, the electronic device 10 includes the radiofrequency system 12, one or more input devices 14, local memory 16, aprocessor core complex 18, one or more main memory storage devices 20, apower source 22, one or more input/output ports 24, and an electronicdisplay 26. The various components described in FIG. 1 may includehardware elements (e.g., circuitry), software elements (e.g., atangible, non-transitory computer-readable medium storing instructions),or a combination of both hardware and software elements. It should benoted that the various depicted components may be combined into fewercomponents or separated into additional components. For example, thelocal memory 16 and a main memory storage device 20 may be included in asingle component.

As depicted, the processor core complex 18 is operably coupled withlocal memory 16 and the main memory storage device 20. Thus, theprocessor core complex 18 may execute instruction stored in local memory16 and/or the main memory storage device 20 to perform operations, suchas instructing the radio frequency system 12 to communicate with anotherelectronic device and/or a network. As such, the processor core complex18 may include one or more general purpose microprocessors, one or moreapplication specific processors (ASICs), one or more field programmablelogic arrays (FPGAs), or any combination thereof.

In addition to the instructions, the local memory 16 and/or the mainmemory storage device 20 may store data to be processed by the processorcore complex 18. Thus, in some embodiments, the local memory and/or themain memory storage device 20 may include one or more tangible,non-transitory, computer-readable mediums. For example, the local memory16 may include random access memory (RAM) and the main memory storagedevice 20 may include read only memory (ROM), rewritable non-volatilememory such as flash memory, hard drives, optical discs, and the like.

As depicted, the processor core complex 18 is also operably coupled withthe I/O ports 24. In some embodiments, the I/O ports 24 may enable theelectronic device 10 to interface with other electronic devices. Forexample, a portable storage device may be connected to an I/O port 24,thereby enabling the processor core complex 18 to communicate data witha portable storage device.

Additionally, as depicted, the processor core complex 18 is operablycoupled to the power source 22. In some embodiments, the power source 22may provide power to one or more components in the electronic device 10,such as the processor core complex 18 and/or the radio frequency system12. Thus, the power source 22 may include any suitable energy source,such as a rechargeable lithium polymer (Li-poly) battery and/or analternating current (AC) power converter.

Furthermore, as depicted, processor core complex 18 is operably coupledwith the input devices 14. In some embodiments, the input device 14 mayfacilitate user interaction with the electronic device 10, for example,by receiving user inputs. Thus, the input devices 14 may include abutton, a keyboard, a mouse, a trackpad, and/or the like. Additionally,in some embodiments, the input devices 14 may include touch-sensingcomponents in the electronic display 26. In such embodiments, thetouch-sensing components may receive user inputs by detecting occurrenceand/or position of an object touching the surface of the electronicdisplay 26.

In addition to enabling user inputs, the electronic display 26 maydisplay image frames, such as a graphical user interface (GUI) for anoperating system, an application interface, a still image, or videocontent. As depicted, the electronic display 26 is operably coupled tothe processor core complex 18. In this manner, the electronic display 26may display image frames based at least in part on image data receivedfrom the processor core complex 18.

As depicted, the processor core complex 18 is also operably coupled withthe radio frequency system 12. As described above, the radio frequencysystem 12 may facilitate wireless communication of data with anotherelectronic device and/or a network. For example, the radio frequencysystem 12 may enable the electronic device 10 to communicatively coupleto a personal area network (PAN), such as a Bluetooth network, a localarea network (LAN), such as an 802.11x Wi-Fi network, and/or a wide areanetwork (WAN), such as a fourth-generation wireless technology (4G), 5G,or LTE cellular network. In other words, the radio frequency system 12may enable wirelessly communicating data using various communicationprotocols and/or at various output powers (e.g., strength of transmittedanalog wireless signals).

As mentioned previously, the radio frequency system 12 may be tailoredto better support wireless transmission via certain wirelesstechnologies. In one embodiment, the radio frequency system 12 mayinclude hardware and/or software that supports mmWave communications onhigh frequency bands (e.g., 10-400 GHz), such as 5G NR mmWave technologyor sub-6 GHz technologies. Thus, in some embodiments, the radiofrequency system 12 may include one or more antenna elements 28, ammWave module (e.g., radio frequency integrated circuit (RFIC)) 30 thatincludes one or more quads 32 associated with the antenna elements 28,and transceiver circuitry (e.g., filters, power dividers, and the like)plus modem 33. The one or more antenna elements 28 may facilitatereceiving and/or transmitting wireless signals using the 5G NR mmWavetechnology.

Further, the radio frequency system 12 may include the mmWave module 30,which in turn includes one or more quads 32 that further facilitatewireless signal transmission and reception. For example, each of thequads 32 may be electrically coupled to one or more antenna elements 28and may include one or more RX paths and TX paths to form a phased arrayantenna that transmits and/or receives wireless signals via beams. Thebeams may be formed by constructive/destructive interference of signalstransmitted and/or received by each antenna 28. Additionally, and asdiscussed in more detail below, the quads 32 may be used to detect thepresence of a nearby object, for example, to adjust radio frequencysystem 12 operations to meet maximum permissible exposure (MPE) formmWave systems or specific absorption rate (SAR) specifications forsub-6 GHz systems. In particular, the one or more quads 32 may transmita reference signal to an external environment and may detect areflection of the reference signal. The radio frequency system 12 maycompare a strength of the reference signal and a strength of thereflected signal to determine whether the results of the comparisonexceed a comparison threshold that correlates to the specific absorptionrate. Based on the determination, the radio frequency system 12 mayadjust energy output by the radio frequency system to below thecomparison threshold.

Additionally, the radio frequency system 12 may include the transceivercircuitry and modem 33 that further processes the wireless signals tofilter noise, amplify signals, and the like. By way of example, thetransceiver circuitry and modem 33 may facilitate performing across-correlation measurement on a received signal and a transmittedsignal.

As described above, the electronic device 10 may be any suitableelectronic device. To help illustrate, one example of a suitableelectronic device 10, specifically a handheld electronic device 10A, isshown in FIG. 2 . In some embodiments, the handheld electronic device10A may be a portable phone, a media player, a personal data organizer,a handheld game platform, and/or the like. For example, the handheldelectronic device 10A may be a smart phone, such as any iPhone® modelavailable from Apple Inc.

As depicted, the handheld electronic device 10A includes an enclosure 34(e.g., housing). In some embodiments, the enclosure 34 may protectinterior components from physical damage and/or shield them fromelectromagnetic interference. Thus, a radio frequency system 12 (notshown) may also be enclosed within the enclosure 34 and internal to thehandheld electronic device 10A. In some examples, the enclosure 34 mayoperate as part of the one or more antenna elements 28 of the radiofrequency system 12.

Additionally, as depicted, the enclosure 34 may surround the electronicdisplay 26. In the depicted embodiment, the electronic display 26 isdisplaying a graphical user interface (GUI) 36 having an array of icons38. By way of example, when an icon is selected either by an inputdevice 14 or a touch sensing component of the electronic display 26, anapplication program may launch.

Furthermore, as depicted, input devices 14 open through the enclosure34. As described above, the input devices 14 may enable a user tointeract with the handheld electronic device 10A. For example, the inputdevices 14 may enable the user to activate or deactivate the handheldelectronic device 10A, navigate a user interface to a home screen,navigate a user interface to a user-configurable application screen,activate a voice-recognition feature, provide volume control, and/ortoggle between vibrate and ring modes. As depicted, the I/O ports 24also open through the enclosure 34. In some embodiments, the I/O ports24 may include, for example, a multi-function connector port (e.g.,Lightning port) to connect to external devices.

To further illustrate, another example of a suitable electronic device10, specifically a tablet electronic device 10B is shown in FIG. 3 . Forexample, the tablet electronic device 10B may be any iPad® modelavailable from Apple Inc. A further example of a suitable electronicdevice 10, specifically a computer 10C, is shown in FIG. 4 . Forexample, the computer 10C may be any Macbook® or iMac® model availablefrom Apple Inc. Another example of a suitable electronic device 10,specifically a watch 10D, is shown in FIG. 5 . For example, the watch10D may be any Apple Watch® model available from Apple Inc.

As depicted, the tablet electronic device 10B, the computer 10C, and thewatch 10D each also include an electronic display 26, input devices 14,I/O ports 24, and an enclosure 34. Thus, in some embodiments, theenclosure 34 may enclose a radio frequency system 12 in the tabletelectronic device 10B, the computer 10C, and/or the watch 10D tofacilitate wireless communication of data with other electronic devicesand/or a network.

As previously mentioned, the hardware of the radio frequency system 12may be tailored to support particular wireless technologies, such asmmWave communication technology. In some embodiments, the radiofrequency system 12 may implement phased array antenna(s), whichincludes multiple antenna elements and multiple quads of TX paths and RXpaths. Such hardware may facilitate transmission and/or reception ofwireless signals according to mmWave communication technology. To ensurecompliance with the MPE or the SAR without compromising on theperformance of the radio frequency system 12, this hardware may beimplemented as a radar/sensor that may detect the presence of the nearbyhuman body in a cost-effective and easily implementable manner.

To help illustrate, an example the radio frequency system hardwareimplemented as a bi-static radar 600 is shown in FIG. 6 , in accordancewith an embodiment. As depicted, the bi-static radar 600 may includemultiple antennas 602, multiple quads 604A-B, one or more cables/traces606, transceiver circuitry 608, and other radio frequency componentsused to transmit and/or receive wireless signals. It should beappreciated that the bi-static radar 600 may include a greater or fewernumber of radio frequency components than shown.

Briefly, the bi-static radar 600 may include the mmWave module 30 withmultiple quads 604A-B that are each coupled to one or more antennas 602(e.g., the antenna element 28). In particular, each antenna 602 may becoupled to a TX/RX chain pair 610 of the quads 604A-B and may transmitwireless signals to or from the TX/RX chain pair 610. For example, thequad 604B may be coupled to the one or more antennas 602 to form aphased array antenna that transmits wireless signals via beams formed byconstructive/destructive interference of signals transmitted by eachantenna 602.

Each of the TX/RX chain pair 610 may include a TX path 612 and a RX path614 that together facilitate transmission and/or reception of wirelesssignals, such as those communicated between electronic devices 10 usingmmWave communication technology or any other suitable communicationprotocol. The TX path 612 and the RX path 614 may be alternativelycoupled to the respective antenna 602 via a switch 616. For example, theswitch 616 may couple to the TX path 612 to enable transmission of thewireless signals to the respective antenna 602. Alternatively, in someembodiments, the respective antenna 602 may be coupled directly to abi-directional coupler 618 in the TX path 612 to enable transmission andreception of the wireless signals.

In some embodiments, the RX path 614 may amplify a received wirelesssignal using an amplifier 620, such as RX Low-Noise Amplifier (LNA) or aRX variable-gain Low-Noise Amplifier (LNA). The amplifier 620 mayamplify an input RX signal received via the respective antenna 602without degrading signal-to-noise ratio (SNR) of the input RX signal(e.g., amplifies power of both the wireless signal and input noise). Theamplified signal may pass through a phase shifter 622 that may modifyphase information programmed into the input RX signal duringtransmission from a different electronic device 10 that generated theinput RX signal. The input RX signal may be further amplified by a RXvariable-gain amplifier (VGA) 624, for example, to compensate for signalstrength loss between the respective antenna 602 and the RX VGA 624.

Each of the RX paths 614 in the quad (e.g., 604A) may subsequentlytransmit the pre-processed input RX signals to a second VGA 626 coupledto each of the TX/RX chain pairs 610. The second VGA 626 may provideadditional amplification of the input RX signal in preparation forfurther processing by the transceiver 608 and/or the modem 644. Althougheach of the quads 604A-B are shown to include four TX/RX chain pairs 610for each frequency band (e.g., 28 GHz, 39 GHz) used by the 5G NR mmWavearchitecture, a greater or fewer number of TX/RX chain pairs 610 may beincluded in each quad 604A-B for each of the frequency bands used.

The input RX signal may then be passed to power dividers (e.g., radiofrequency splitters 1:2, radio frequency splitters 1:4) 628A and one ormore frequency filters 630A, such as a bandpass filter and/or low passfilter. The power dividers 628A and frequency filters 630A may combinefilter the input RX signal to facilitate further processing by the radiofrequency system 12. Once processed by the mmWave module 30, the inputRX signal may be transmitted to the transceiver 608 via traces 606A-B(collectively, “606”), which act as interfaces between the transceiver608 and the quads 604A-B. The traces 606 may be designated as horizontalpolarization traces or vertical polarization traces, such that eitherhorizontal or vertical polarised signals (e.g., electromagnetic waveswith the electric field in the horizontal plane or vertical plane,respectively) are picked up and transmitted via the traces 606. Forexample, the trace 606A may be implemented to transmit signals ofpolarization 1, such as horizontal polarization, while the trace 606Bmay be implemented to transmit signals of polarization 0, such asvertical polarization, or vice versa. In some embodiments, thepolarization of each trace 606 may be configurable.

The transceiver 608 may include additional radio frequency processingblocks. For example, the traces 606 may transmit the input RX signal toadditional power dividers (e.g., 632A) and to an additional set offrequency filters (e.g., 634A) dedicated to processing the input RXsignal. Additional TX/RX paths 636A may be coupled to the frequencyfilters 634A and may transmit the input RX signal for furtherpost-processing. The additional TX/RX paths 636A may be implemented totransmit signals of a particular frequency band (e.g., 28 GHz, 39 GHz).It should be appreciated that the radio frequency processing blocks mayinclude other varieties of processing circuitry, such as adown-converter.

In addition to receiving wireless signals, the radio frequency system 12may also transmit wireless signals to other electronic devices. As anexample, the modem 644 may generate a reference output TX signal that ispre-processed by processing blocks of the transceiver 608, such as adigital pre-distortion processing block, filters 634B, and powerdividers 632B. The output TX signal may be subsequently transmitted tothe mmWave module 30 via the trace (e.g., 608B) coupled to thetransmitting quad (e.g., 604B).

The mmWave module 30 may perform additional filtering and powersplitting operations via the filters 630B and the power dividers 628B.Further, based on the frequency of the output TX signal, the output TXsignal may be transmitted to an appropriate second VGA 638 of the mmWavemodule 30 for amplification before processing by the TX path 612. Onceamplified, the output TX signal may be further amplified by a TX VGA 640of the TX path 612 to compensate for expected strength loss from theconnections and components of the TX path 612.

The output TX signal may then be modulated (e.g., phase shifted) usingthe phase shifter 622. The phase shifter 622 may work with other phaseshifters of the other TX/RX path pairs 610 to form beams of wirelesssignals that may be steered in a particular direction, such as towardsanother electronic device 10. Although a single phase shifter 622 isshown for both the TX path 612 and the RX path 614, it should beappreciated that each TX path 612 and RX path 614 may include their owndedicated phase shifter 622.

Prior to transmission of the output TX signal to the externalenvironment, a power amplifier 642 may amplify the output TX signal toensure that the output TX signal has sufficient range, for example, toreach the target electronic device 10. Once amplified, the output TXsignal may be transmitted to the respective antenna 602, either throughthe switch 616 or through the bi-directional coupler 618.

As previously discussed, the hardware may be implemented as thebi-static radar 600 to detect the presence of objects (e.g., a humanbody) near the electronic device 10. In particular, the bi-static radar600 may use a first quad (e.g., 604B) to transmit the reference outputTX signal as a beam to the external environment. In particular, one ormore TX paths 612 of the first quad (e.g., 604B) may process andtransmit a 5G NR signal (e.g., TX 5G NR signal) generated by the modem644. The TX 5G NR signal 646 may be generated with a frequency allocatedto the 5G NR protocol. For example, the TX 5G NR signal 646 may be of a28 GHz frequency band (e.g., 5G NR band n257, n258, n261) or of a 39 GHz(e.g., 5G NR band n260) frequency band, in accordance with the 3GPPprotocol for Discrete Fourier Transform-spread-Orthogonal FrequencyDivision Multiplexing (DFT-s-OFDM) or Cyclic-Prefix OFDM (CP-OFDM). Thismay ensure that the bi-static radar 600 may function without affectingregular 5G NR cellular communications. Additionally, the TX 5G NR signal646 may be of a first polarization, such as the horizontal polarizationof trace 606B.

When the object, such as a human body 648, is within proximity to theradio frequency system 12, the TX 5G NR signal 6464 may be reflectedback by the human body 648. Generally, the larger the object, thegreater the strength of the reflected signal. Further, the closer theobject to the radio frequency system 12, the greater the strength of thereflected signal.

A second quad (e.g., 604A) may receive the reflected 5G NR signal (e.g.,RX 5G NR signal) 650. In particular, the one or more RX paths 614 of thesecond quad (e.g., 604A) may receive the RX 5G NR signal 650 via thefirst polarization. However, the one or more RX paths 614 may transmitthe RX 5G NR signal 650 back to the transceiver 608 using a secondpolarization, such as the vertical polarization of trace 606A.

Once the RX 5G NR signal 650 has been received by the transceiver 608,the transceiver 608 may transmit the RX 5G NR signal 650 to the modem644. The modem 644 may perform a post-processing comparison between theTX 5G NR signal 646 it previously generated and the received RX 5G NRsignal 650. The comparison may involve performing a cross-correlation ofthe RX 5G NR signal 650 and the TX 5G NR signal 646, which may generatea spectrum that reveals whether an object is present near the radiofrequency system 12. For example, close and narrow peak(s) may revealthat the object is within proximity. In other words, the object iswithin an unacceptable distance threshold for the amount of output powerbeing emitted by the radio frequency system 12. In some embodiments, thedistance threshold for the amount of output power may be determinedbased on the MPE or the SAR. Once the radio frequency system 12determines that an object is within proximity, the radio frequencysystem 12 may adjust output power to comply with the MPE or the SARspecifications (e.g., reduce output power to meet an energy absorptionthreshold).

By implementing the hardware as the bi-static radar 600, this techniquefor detecting the presence of the object may have better dynamic range.In particular, the RX paths 614 used to detect the RX 5G NR signal 650may have enhanced signal sensitivity without using additional amplifiersand thus, increased ability to detect the RX 5G NR signal 650, even ifthe RX 5G NR signal 650 is relatively weak (e.g., due to reflection offof a relatively distant object). Further, the detection sensitivity maybe increased when multiple RX paths 614 are used to detect the RX 5G NRsignal 650. Additionally, to increase signal-to-noise ratio (SNR) of theRX 5G NR signal 650 and the TX 5G NR signal 646, all of the available TXpaths 612 and the RX paths 614 may be used to transmit and receive the5G NR signal.

The radio frequency hardware may be additionally or alternativelyimplemented as a mono-static radar 700 that may detect the presence ofthe nearby object, as shown in FIG. 7 in accordance with an embodiment.The hardware of the mono-static radar 700 may have similar functionalityas the hardware of the bi-static radar 600. For example, the multiple RXpaths 614 and multiple TX paths 612 of the mmWave module 30 mayfacilitate transmission and reception of wireless signals, thetransceiver 608 may perform processing operations on the transmitted andreceived signals, and the modem 644 may compare the transmitted andreceived signals to detect nearby objects.

However, the mono-static radar 700 may operate in a different mannerthan the bi-static radar 600. In particular, the mono-static radar 700may use a single quad (e.g., 604B), rather than multiple quads 604A-B,to determine the presence of the nearby human body. For example, one ormore TX paths 612 of the single quad (e.g., 604B) may process andtransmit a 5G NR signal (e.g., TX 5G NR signal) 702 generated by themodem 644 and of a frequency allocated to the 5G NR protocol. Forexample, the TX 5G NR signal 702 may be of a 28 GHz frequency band(e.g., 5G NR band n257, n258, n261) or of a 39 GHz (e.g., 5G NR bandn260) frequency band, in accordance with the 3GPP protocol forDFT-s-OFDM or CP-OFDM. This may ensure that the mono-static radar 700may function without affecting regular 5G NR cellular communications.Additionally, the TX 5G NR signal 702 may be polarized, such as thehorizontal polarization of trace 606B.

The TX 5G NR signal 702 may be transmitted to the respective antenna 602via the bi-directional coupler 618 and eventually to the externalenvironment by the respective antenna 602. When the external environmentincludes an object, such as a human body 704, near the radio frequencysystem 12, the TX 5G NR signal 702 may be reflected by the human body704.

The reflected 5G NR signal (e.g., RX 5G NR signal) 706 may be detectedby the antenna element 28 (e.g., one or more antennas 602) of the singlequad (e.g., 604B). During detection of the RX 5G NR signal 706, the oneor more antennas 602 may be coupled to the TX path 612. In someembodiments, to transmit the RX 5G NR signal 706 to the transceiver 608and the modem 644 using the same transmitting polarization, themono-static radar 700 may use the bi-directional coupler 618 in each ofthe TX path 612, the envelope detector(s) 708, and the ADC 710.

In particular, the bi-directional coupler 618 may be coupled to arespective envelope detector 708 associated with a respective TX path612. The bi-directional coupler 618 of a receiving RX path 614 maytransfer a portion of the RX 5G NR signal 706 to the envelope detector708. The bandwidth of the envelope detector 708 may allow the envelopedetector 708 to recover an envelope signal of the RX 5G NR signal 706 asopposed to other signal recover detectors, such as root-mean-square(RMS) detectors. The envelope detector 708 may be coupled to the ADC710, which may generate a digital representation of the RX envelopesignal. Once digitized, the digital representation may be transmitted tothe transceiver 608 and to the modem 644 for post-processing.

As previously described, the modem 644 may perform a post-processingcomparison between the TX 5G NR signal 702 and the RX 5G NR signal 706.In particular, the modem 644 may have the TX 5G NR signal 702 storedfrom the generation of the TX 5G NR signal 702 and may also receive thedigitized RX envelope signal. Additionally or alternatively, the modem644 may also receive a digitized TX envelope signal that is generated ina similar manner at the digitized RX envelope signal. The modem 644 maysubsequently determine a phase difference (e.g., delay between the TXenvelope signal and the RX envelope signal) between the digitizedenvelope signals and may perform a cross-correlation on the digitizedenvelope signals. The cross-correlation may generate a spectrum that mayreveal whether the object is present near the radio frequency system 12.For example, close and narrow peak(s) may reveal that the object iswithin proximity. In other words, the object is within an unacceptabledistance threshold for the amount of output power being emitted by theradio frequency system 12. In some embodiments, the distance thresholdfor the amount of output power may be determined based on the MPE or theSAR. Once the radio frequency system 12 determines that an object iswithin proximity, the radio frequency system 12 may adjust output powerto comply with the MPE or the SAR specifications (e.g., reduce outputpower).

By implementing the hardware as the mono-static radar 700, thistechnique for detecting the presence of the object may be independent ofpolarization effects on the TX 5G NR signal 702 and the RX 5G NR signal706 since only a single quad (e.g., 604B) and a single polarized trace(e.g., 606B) are used. Further, to increase signal-to-noise ratio (SNR)of the TX 5G NR signal 702 and the RX 5G NR signal 706, multiple TXpaths 612 and RX paths 610 may be used to transmit and receive the 5G NRsignal. Furthermore, the bi-directional coupler 618, envelope detector708, and ADC 710 may enable measurement of both the TX 5G NR signal 702and the RX 5G NR signal 706 without relying on use of the RX paths 614.

Additionally or alternatively, the hardware of the radio frequencysystem 12 may be implemented as a specialized Body Detection Sensoroperating in the 24 giga-hertz (GHz) band (e.g., 24 GHz sensor) 800, asshown in FIG. 8 in accordance with an embodiment. The hardware of the 24GHz sensor 800 may have similar functionality as the hardware of thebi-static radar 600. For example, the multiple RX paths 614 and multipleTX paths 612 of two quads 604A-B in the mmWave module 30 may facilitatetransmission and reception of wireless signals. Further, the transceiver608 may perform processing operations the transmitted and receivedsignals, and the modem 644 may compare the transmitted and receivedsignals to detect nearby objects.

However, the 24 GHz sensor 800 may operate using a chirp signal ratherthan a 5G NR signal. In particular, the mmWave module 30 and theantennas 602 may include circuitry that can transmit, receive, andprocess wireless signals between the frequencies 24 to 24.25 GHz. Themodem 644 may generate a chirp signal (e.g., non-5G NR impulse responsesignal) that may be transmitted to a first quad (e.g., 604B) using afirst polarization and subsequently to the external environment. Thechirp signal may be transmitted during measurement gaps (e.g., 10-80 msgap during which an electronic device 10 is not transmitting orreceiving communication) defined by the 3GPP 5G NR standard.

The transmitted chirp signal 802 may be reflected off of a nearbyobject, such as a human body 804. The reflected chirp signal 806 may bereceived by one or more TX paths 164 of the second quad (e.g., 604A),which may be subsequently relayed back to the transceiver 608 and to themodem 644 using a second polarization. As previously described, themodem 644 may perform a post-processing comparison between the TX chirpsignal 802 and the RX chirp signal 806. In particular, the modem 644 mayperform a cross-correlation of the digitized TX envelope signal and thedigitized RX envelope signal. The cross-correlation may yield a spectrumthat reveals whether the object is present near the radio frequencysystem 12. For example, close and narrow peak(s) may reveal that theobject is within proximity. In other words, the object is within anunacceptable distance threshold for the amount of output power beingemitted by the radio frequency system 12. In some embodiments, thedistance threshold for the amount of output power may be determinedbased on the MPE or the SAR. Once the radio frequency system 12determines that an object is within proximity, the radio frequencysystem 12 may adjust output power to comply with the MPE or the SARspecifications (e.g., reduce output power).

By implementing the hardware as the 24 GHz sensor 800, this techniquemay enable flexibility in detecting the presence of the object. Forexample, a chirp signal used in industrial radar applications may beused instead of a 5G NR signal due to the use of a 24 GHz band outsideof the 5G radio bands. Thus, this technique may also be compatible withsub-6 GHz technologies. Additionally, because the chirp signal may betransmitted during measurement gaps defined by the 3GPP 5G NR standard,this technique may not affect the 5G NR cellular communications.

Further, it should be appreciated that the 24 GHz sensor 800 may operatein a manner similar to that of the mono-static radar 700. For example,the 24 GHz sensor 800 may use a single quad (e.g., 604B) and singlepolarization to transmit and receive the chirp signal. The 24 GHz sensor800 may also use the bi-directional coupler 618, the envelope detectors708, and the ADC 710 to transmit digitized, envelope signals of thetransmitted and reflected chirp signals to the modem 644. Byimplementing the 24 GHz sensor 800 in a manner similar to that of themono-static radar 700, the technique may be independent of polarizationeffects on the transmitted and reflected chirp signals.

A process 900 for adjusting operations of the radio frequency system 12based at least in part on the detection of the object is described inFIG. 9 , in accordance with an embodiment. While process 900 isdescribed according to a certain sequence, it should be understood thatthe present disclosure contemplates that the described steps may beperformed in different sequences than the sequence illustrated, andcertain described steps may be skipped or not performed altogether. Insome embodiments, the process 900 may be implemented at least in part byexecuting instructions stored in a tangible, non-transitory,computer-readable medium, such as the memory 20, using processingcircuitry, such as the processor core complex 18 or a separatecontroller designated for the radio frequency system. Additionally oralternatively, the process 900 may be implemented at least in part bycircuit connections and/or control logic implemented in an electronicdevice 10.

Generally, the process 900 may be initiated by configuring the radiofrequency hardware as a bi-static radar 600, a mono-static radar 700, ora 24 GHz sensor 800 (process block 902). In particular, the processorcore complex 18 may instruct the mmWave RFIC hardware to use a singlequad (e.g., 604A) or multiple quads 604A-B implement either the radarconfiguration or the sensor configuration. The processor core complex 18may instruct the mmWave module 30 hardware to use a single quad (e.g.,604A) or multiple quads 604A-B. The processor core complex 18 may theninstruct the radio frequency system 12 to transmit the selected signalto the external environment (process block 904). For example, one ormore of the TX paths 612 may process and transmit the selected signal.The radio frequency system 12 may subsequently receive a reflection ofthe transmitted signal when the transmitted signal is reflected of thenearby object (process core complex 906).

Furthermore, the processor core complex 18 may instruct the modem 644 toperform a comparison between the transmitted signal and the reflectedsignal (process block 908). For example, the modem 644 may perform thecross-correlation measurement on the transmitted signal and thereflected signal. Once the comparison is complete, the electronic device10 may determine whether the object is within proximity of the radiofrequency system 12 (decision block 910). That is, the spectrumgenerated from the cross-correlation measurement may be used todetermine whether the object is nearby. The cross-correlationmeasurements may be compared to a comparison threshold correlated to theMPE or the SAR specifications. When it is determined that the object isnearby (e.g., the comparison results exceed the comparison threshold),the power output by the radio frequency system 12 may be decreased tomeet the MPE or the SAR (process block 912). If the object is not withinproximity, then the radio frequency system 12 may increase or maintainthe power output of the radio frequency system 12 (process block 914).

By employing the techniques described above, the radio frequency system12 may detect the presence of the nearby object and adjust system 12operations to meet the MPE for mmWave operations or the SAR for thesub-6 GHz operations. Further, the present techniques provide objectdetection using existing radio frequency circuitry rather via dedicatedradar circuitry (e.g., 60 GHz body proximity sensor radar) which mayincrease silicon area if integrated in the radio frequency circuitry.Additionally, the present techniques provide flexibility in the dynamicrange offered during detection by varying the number of TX paths 612and/or RX paths 614 used to transmit and receive the signals,respectively.

The specific embodiments described above have been shown by way ofexample, and it should be understood that these embodiments may besusceptible to various modifications and alternative forms. It should befurther understood that the claims are not intended to be limited to theparticular forms disclosed, but rather to cover all modifications,equivalents, and alternatives falling within the spirit and scope ofthis disclosure.

What is claimed is:
 1. A millimeter wave radio frequency system,comprising: a first circuit, configured to transmit data over a firstone or more frequency bands, the first circuit further configured totransmit a reference signal over a second one or more frequency bandsoutside the first one or more frequency bands; a second circuitconfigured to receive a reflection signal in the second one or morefrequency bands based on the reference signal; and a processorconfigured to instruct the millimeter wave radio frequency system toperform a comparison between the reference signal and the reflectionsignal, determine that an object is in proximity to the millimeter waveradio frequency system based on the comparison exceeding a comparisonthreshold, and in response to determining that the comparison exceedsthe comparison threshold, decrease power output of communications of thefirst circuit over the first one or more frequency bands.
 2. Themillimeter wave radio frequency system of claim 1, wherein the secondone or more frequency bands comprise industrial, scientific, and medical(ISM) bands.
 3. The millimeter wave radio frequency system of claim 1,wherein the millimeter wave radio frequency system is configured tocommunicate the reference signal during a measurement gap fromcommunicating over the first one or more frequency bands.
 4. Themillimeter wave radio frequency system of claim 1, wherein the referencesignal comprises industrial radar waveforms.
 5. The millimeter waveradio frequency system of claim 1, wherein the first circuit comprisesone or more transmission paths configured to transmit and processsignals generated by the millimeter wave radio frequency system, thesecond circuit comprises one or more reception paths configured toreceive and process signals transmitted by an external electronicdevice.
 6. The millimeter wave radio frequency system of claim 5,wherein the first circuit comprises one or more additional receptionpaths and the second circuit comprises one or more additionaltransmission paths, and wherein the millimeter wave radio frequencysystem comprises a switch configured to control whether the secondcircuit receives the signals or transmits the signals.
 7. The millimeterwave radio frequency system of claim 5, wherein the one or moretransmission paths are configured to transmit the reference signal via afirst polarization, and wherein the one or more reception paths areconfigured to receive the reflection signal via a second polarization.8. The millimeter wave radio frequency system of claim 1, wherein thefirst one or more frequency bands comprise fifth generation new radiofrequency bands.
 9. The millimeter wave radio frequency system of claim1, comprising a modem coupled to the first circuit and the secondcircuit, wherein the modem is configured to perform the comparisonbetween the reference signal and the reflection signal.
 10. Themillimeter wave radio frequency system of claim 1, wherein thecomparison threshold is associated with a level of energy absorption,and wherein the comparison comprises a cross-correlation measurement ofthe reference signal and the reflection signal.
 11. The millimeter waveradio frequency system of claim 1, wherein in response to determiningthat the comparison is below the comparison threshold, maintain orincrease power output.
 12. The millimeter wave radio frequency system ofclaim 1, wherein the comparison threshold is based at least in part on amaximum permissible exposure (MPE) specification for millimeter wave(mmWave) systems, specific absorption rate (SAR) specification for sub-6GHz systems, or any combination thereof.
 13. A circuit, comprising: anantenna element configured to transmit and receive wireless signals; oneor more transmission paths coupled to the antenna element, the one ormore transmission paths are configured to process a reference signal ofa selected polarization, and transmit the reference signal from anelectronic device comprising the circuit using the selectedpolarization, the reference signal transmitted during a measurement gapof communicating the wireless signals, and one or more receiving pathscoupled to the antenna element, the one or more receiving paths areconfigured to receive a reflection signal based on the reference signalusing the selected polarization; wherein the circuit is configured todetermine whether an object is in proximity to the electronic devicebased at least in part on a comparison between the reference signal andthe reflection signal, and in response to the object being in proximityto the electronic device, decrease power output by the circuit.
 14. Thecircuit of claim 13, wherein the one or more transmission paths areconfigured to transmit the reference signal over an industrial,scientific, and medical (ISM) band.
 15. The circuit of claim 13, whereinat least a first portion of the one or more transmission paths areconfigurable to transmit the reference signal and at least a secondportion of the one or more transmission paths are configurable to nottransmit the reference signal, and wherein at least a first portion ofthe one or more receiving paths are configurable to receive thereflection signal and at least a second portion of the one or morereceiving paths are configurable to not receive the reflected signal.16. The circuit of claim 13, wherein the measurement gap is defined by astandard for communicating the wireless signals.
 17. The circuit ofclaim 13, comprising: one or more bi-directional couplers coupled to theone or more transmission paths and the antenna element, the one or morebi-directional couplers configured to transmit the reference signal andthe reflection signal to one or more envelope detectors.
 18. The circuitof claim 17, wherein the one or more envelope detectors are configuredto generate an envelope signal for each signal transmitted to the one ormore envelope detectors from the one or more bi-directional couplers,the one or more envelope detectors configured to digitize the envelopesignals, as digitized envelope signals.
 19. The circuit of claim 18,wherein determining whether the object is in proximity to the electronicdevice comprises comparing the digitized envelope signals of thereflection signal and the digitized envelope signals of the referencesignal via cross-correlation.
 20. A method, comprising: transmitting,via a communication circuitry, data over a first one or more frequencybands and a reference signal over a second one or more frequency bandsoutside the first one or more frequency bands; receiving, via thecommunication circuitry, a reflection signal based on a reflection ofthe reference signal off an object; comparing, via the communicationcircuitry, the reflection signal and the reference signal; determining,via the communication circuitry, whether the object is within apre-defined proximity to an electronic device comprising thecommunication circuitry; in response to the object being within thepre-defined proximity, decreasing power output by the electronic device;and in response to the object not being within the pre-definedproximity, increasing power output by the electronic device.